1. Field of the Disclosure
The present invention relates generally to power converters. More specifically, examples of the present invention are related to controlling a power converter in response to certain signals from the power converter.
2. Background
Switch mode power converters are widely used for household or industrial appliances that require a regulated direct current (dc) source for their operation, such as for example battery chargers that are commonly used in electronic mobile devices. Off-line ac-dc converters convert a low frequency (e.g., 50 Hz or 60 Hz) high voltage ac (alternating current) input voltage to a required level of dc output voltage. Various types of switch mode power converters are popular because of their well regulated output, high efficiency, and small size along with their safety and protection features. Popular topologies of switch mode power converters include flyback, forward, boost, buck, half bridge, and full bridge, among many others including resonant types.
A major challenge in the market of switch mode power converters is reducing the size and cost of the switch mode power converter while maintaining high performance operating specifications, including efficiency. To increase efficiency, power converters may include a control circuit to control switches and/or other circuitry in the power converter in response to sensing certain input signals at specific nodes of the power converter. In some applications, the control circuit may control a switch in response to an input signal that may vary between a relatively wide range of voltages. Furthermore, the control circuit may need to detect that the input signal has crossed a certain threshold and adjust an output signal accordingly. It may also be desirable for the control circuit to quickly respond to a given input signal in order to increase the efficiency of the power converter. In some instances, the threshold may be a voltage that is below the negative supply voltage rail of the control circuit. In some instances, the threshold may be low (small in magnitude).
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.